In the prior art, energy guiding chains are known in which the chain links are formed by parallel side-plates or straps connected by cross-members, where the straps have lateral locking projections facing the inside of the chain for the detachable, snap-in accommodation of correspondingly designed cross-members or connectors. Energy guiding chains of this kind serve to guide cables, hoses and similar energy lines from one connecting point to another connecting point, where the position of at least one of the connecting points is variable.
An example of an energy guiding chain of the type described above is known from DE 35 31 066 A1 U.S. Pat. No. 4,513,224 granted Mar. 21, 1989. The energy guiding chain described there essentially consists of straps provided alternately with pins and circular bore holes, where the straps are connected to one another by way of detachable upper and lower cross-members to form a single chain link, where the pins of one chain link snap into the bore holes of the next chain link, so that the chain links can pivot relative to one another. in order to accommodate the detachable upper and lower cross-members, the straps are provided with inward-pointing projections or snap pins, which snap into recesses of the cross-members. The cross-members are easily and captively connected to the straps by being snapped onto the snap pins of the straps. Due, in particular, to the fact that the straps which respectively make up a single chain link are of mirror-image design with respect to one another, and that the upper and lower cross-members are identical, the known energy guiding chain is simple to manufacture and easy to assemble.
Another similar energy guiding chain is known from German Patent DE 39 09 797. This energy guiding chain also consists of similar parallel straps which can pivot relative to one another, which are connected to one another by way of detachable upper and lower cross-members, where the ends of the cross-members are attached in a detachable manner to straps positioned at the same height. In the case of this known energy guiding chain, the centre region of each chain strap is provided on both sides of the middle longitudinal plane of the chain strap with upper and lower projections, each of which having a T-shaped groove for accommodating the correspondingly shaped ends of the cross-members. The ends of the cross-members are of T-shaped design and can be inserted from the side into the grooves formed by the projections.
In order to increase the effective cross-section of the chain, German Patent DE 39 09 797 proposes retrofittable, oblong adapters, which can be inserted in pairs into the T-shaped grooves of two straps positioned at the same height and which accommodate cross-members in between having the same design and the same fastening elements as the chain cross-members of the straps. These adapters are seated with one wall on the upper or lower edge of the straps and thus form an extension of the middle longitudinal plane of the straps. Consequently, only a two-strap chain is required, to which elements can be attached using the adapters to accommodate cables in addition to the cables or lines of this chain, so that the effective cross-section and thus the capacity of the chain can be substantially increased, where cross-members of identical design can always be used.
The solution proposed in German Patent DE 39 09 797 may have the advantage that cross-members of identical design can always be used, but it involves the disadvantage that the assembly of the elements which increase the effective cross-section of the chain is very complicated. Each adapter must always be mounted on each strap individually, which means that, if necessary, a total of four adapters must be mounted on each chain link and, in addition, one or more cross-members must be mounted in between them. Since the cross-members are inserted into T-shaped grooves extending in the longitudinal direction of the chain, it is complicated to subsequently open the energy guiding chain in order to insert or remove cables. For example, if several cross-members are mounted one above the other as separators in order to partition the inside of the expanded cross-section or the original chain cross-section, the chain must virtually be disassembled entirely in order to insert cables into the chain cross-section bounded by the actual straps.
Furthermore, in the design described above, the width of the expanded cross-section is predefined by the distance between the straps defining the width of the chain. For example, this makes it impossible to construct an expanded cross-section which is offset or asymmetrical in relation to the original chain cross-section defined by the straps.
In addition, the existence of only two different types of parts, namely adapters and cross-members, permits only a few design alternatives as regards the construction and partitioning of the expanded cross-section.
However, the most serious disadvantage of the known chain is the fact that it is more difficult to subsequently open the chain in order to insert or remove cables.
A tubular, virtually completely closed energy guiding chain is known from U.S. Pat. No. 3,779,003 granted Dec. 18, 1973, for example, whose links consist of a U-shaped base and a U-shaped cover which fits over the base. The U-shaped covers are provided with snap tabs, which fit over the sides of the base forming the respective chain link and snap into corresponding recesses. The covers described in U.S. Pat. No. 3,779,003 form a closed, tubular energy guiding chain such that the pivotal axes of the individual links are positioned below the middle longitudinal plane of the cable guide in order to permit a certain degree of sag. This results in the asymmetrical shape of the individual chain link or chain cross-section in relation to the pivotal axis of the links. The effective cross-section of the chain is not intended to be expanded in this way. The effective cross-section of the chain described there is defined, and the ratio of the height of the sides of the chain links to the height of the covers is defined by the desired sag of the chain. German Patent DE 37 30 586 C1 describes the use of multi-part cross-members for an energy guiding chain, where the cross-members exhibit a centre section of adjustable length, in order to design the width of the interior space for the energy lines in such a way that it can be adapted to the thickness of the inserted energy lines. The cross-members are adjusted by cutting profile sections of the respective cross-members to the desired length. In this case, the effective cross-section is only expanded in terms of the width of the chain, where adjusting the chain in this way is very complicated and virtually irreversible if no additional material is used.